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WR Meadows PRECON Pre-Applied Underslab Waterproofing Membrane 4 ft x 50 ft Roll
WR Meadows PRECON is a pre-applied composite sheet membrane of non-woven fabric, elastomeric membrane and a seven-layer PLASMATIC CORE, supplied in a 4 ft x 50 ft roll (200 sq ft). It is intended for blindside walls where the positive side can't be reached, and for underslab waterproofing and vaporproofing.
- Concrete poured against the fabric side forms a mechanical bond as it cures
- Goes on at temperatures down to 40 F (5 C); pour concrete within 60 days
- Water vapor transmission of 0.006 perms (ASTM E96B)
$626.98
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WR Meadows PRECON Pre-Applied Underslab Waterproofing Membrane 4 ft x 50 ft Roll
WR Meadows PRECON (often searched as precon wr meadows) is a composite sheet membrane made of a non-woven fabric, an elastomeric membrane and the WR Meadows PLASMATIC CORE, a seven-layer matrix intended for toughness and low water vapor transmission. Once concrete is poured against PRECON and cures, a mechanical bond forms that secures the concrete to the membrane. It is used as a blindside membrane on vertical walls where access to the positive side is limited, such as against lagging, soil retention or caisson wall shoring, and horizontally for underslab waterproofing and vaporproofing. It also reduces methane and radon gas intrusion. Laps, terminations and penetrations are detailed with BEM, HYDRALASTIC 836 or MEL-ROL LIQUID MEMBRANE and DETAIL FABRIC. PRECON goes on at temperatures down to 40 F (5 C); for marginal conditions below 60 F (16 C), WR Meadows makes PRECON WINTER-GRADE.
Key Features
- 73 mil composite: non-woven fabric, elastomeric membrane and seven-layer PLASMATIC CORE
- Mechanical bond to the concrete poured against it
- Water vapor transmission of 0.006 perms (ASTM E96B)
- Hydrostatic pressure resistance of 231 ft (ASTM D5385)
- Reduces methane and radon gas intrusion
Applications
- Blindside foundation walls against lagging, soil retention or caisson wall shoring
- Underslab waterproofing and vaporproofing
- Vapor mitigation barrier, where the design professional of record approves it
- Below-grade structures where access to the positive side is limited
Technical Specifications
| Property | Value |
|---|---|
| Type | Pre-applied blindside and underslab waterproofing membrane |
| Construction | Non-woven fabric, elastomeric membrane and seven-layer PLASMATIC CORE |
| Roll size | 4 ft (1.2 m) wide x 50 ft (15.2 m) long, one roll per carton |
| Coverage per roll | 200 sq ft (18.6 m²) gross; 175 sq ft (16.26 m²) net with a 6 Inch overlap |
| Thickness (ASTM D1000) | 73 mil (1.85 mm) |
| Low temperature flexibility (ASTM D1970) | 180° bend at -20 F (-28.9 C), pass |
| Hydrostatic pressure resistance (ASTM D5385) | 231 ft (70 m) |
| Elongation, polymeric membrane (ASTM D412) | > 400% |
| Tensile strength, film (ASTM D882) | 9200 psi (63.4 MPa) |
| Crack cycling (ASTM C836) | Pass at -15 F (-26 C) |
| Puncture resistance (ASTM E154) | > 210 lb (> 934 N) |
| Peel adhesion to concrete (ASTM D903) | 10 lb/in (1754 N/m) |
| Lap peel adhesion (ASTM D1876) | 5.60 PLI |
| Water vapor transmission (ASTM E96B) | 0.006 perms (0.041 g/m²/24 hr) |
| Radon transmittance | <3.0 x 10-9 m/s |
| Methane gas transmission rate (ASTM D1434) | 43 mL/day·m²·atm |
| Resistance to fungi in soil | 16 weeks, no effect |
| Application temperature | Down to 40 F (5 C); below 40 F, contact WR Meadows technical services |
| Time to pour | Concrete within 60 days of membrane installation |
| Specifications | LARR Report 26023 |
| Pack | 4 ft x 50 ft roll |
| Part number | 5118050 |
Product documents: WR Meadows PRECON Data Sheet (PDF)
Frequently Asked Questions
How much area does one roll of WR Meadows PRECON cover?
Each 4 ft x 50 ft roll gives 200 sq ft (18.6 m²) gross, or 175 sq ft (16.26 m²) net with the 6 Inch overlap.
At what temperature can PRECON go on?
PRECON may be applied at temperatures down to 40 F (5 C). In less-than-ideal or marginal conditions below 60 F (16 C), WR Meadows suggests PRECON WINTER-GRADE, which installs at 20 F (-7 C) and rising. For installations below 40 F, contact WR Meadows technical services. When conditions warrant, use solvent-based MEL-PRIME to strengthen the bond at the selvage edge; MEL-PRIME W/B is not recommended for cold-temperature installation.
How is PRECON installed on a blindside wall?
Attach MEL-DRAIN to the lagging or soil retention system first. Fasten the membrane every 12 Inch across the top, within 1/2 Inch of the top edge, with the fabric side facing the concrete pour. Remove the release paper on the 6 Inch overlap and roll press with a tile-type roller. Without a drainage board the substrate must be sound, solid and smooth, and gaps or voids over 1 Inch must be grouted; with MEL-DRAIN the system bridges gaps under 2 Inch.
How are laps, terminations and penetrations detailed?
Overlap end laps 6 Inch and apply BEM, HYDRALASTIC 836 or MEL-ROL LIQUID MEMBRANE in the lap before roll pressing. At terminations, apply one of those materials 12 Inch wide, centered on the termination, and embed 12 Inch DETAIL FABRIC while it is wet, 6 Inch on each side. At penetrations, form a fillet that overlaps the fabric side and the protrusion at least 2.5 Inch, adding DETAIL FABRIC where the gap is over 1/2 Inch. For a cluster of horizontal penetrations, use HYDRALASTIC 836 in a pitch pan formed from 2 x 4 lumber.
What has to happen before the concrete pour?
Pour the concrete within 60 days of installing the membrane. Inspect for punctures or damage and repair with HYDRALASTIC 836 and/or DETAIL FABRIC, and clear standing water and any material that would affect the bond. Use bar supports with a flat bottom. For underslab work, prepare the subgrade per ACI 302.1R-04, Chapter 4.
Can PRECON be used as a vapor mitigation barrier?
PRECON reduces methane and radon gas intrusion, and the data sheet publishes gas diffusion data for common solvents. The licensed design professional of record decides whether it suits a project as the vapor mitigation barrier, based on that data and local regulations. WR Meadows suggests a passive (convertible to active) or active venting system above the barrier, and installing PRECON in clean soil to avoid contact with liquid contaminants.
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